The present invention relates to a heat sink for use with an electronic component, and, more particularly, to an assembly of an electronic component and a heat sink that can be readily manufactured and assembled.
There are, of course, many types and construction of heat sinks that are used to conduct heat away from electronic components. The heat sinks are normally provided in the form of heat sink assemblies that combine the heat sink itself with the heat generating electronic component. The main purpose of the heat sink assembly is to locate, secure and protect all of the heat sinks in a particular machine. As examples, all welding power sources have heat generating electronic components, and some of those components require an additional means of dissipating the heat produced. Thus, with such electronic components, heat sinks are used to dissipate that heat and such electronic components can include diodes, IGBTs, resistors or any other of the electronic components used in various differing type of apparatus.
With present electronic components used in welding apparatus, the heat generating electronic component can be assembled individually into a standard package or can be assembled into a module type of package that may house a plurality of the electronic components and either the single mounting or module type of mounting can be obtained commercially. However, with the individual package, while the cost is relatively inexpensive to the user, there is a need to purchase many of the devices to assemble a welding power source and the sheer number of individual devices make it very difficult to assemble the overall power source with the traditional types of assembly methods. On the other hand, with the modular package, the assembly of the multiple electronic component is simplified since there are less devices to assembly, however the module form of heat sink assembly is more expensive than the purchase of many individual devices.
As such, there is also a need to make the manufacturability of the heat sink devices to be as inexpensive as possible and to use mass production techniques in the assembly of the heat sink to the electronic component. Traditionally, one means of attaching the heat generating electronic component to the heat sink is by means of a threaded mounting, such as screws, and then the heat sink and the device assembly is mounted to the frame of the power source with additional screws or other mounting means. If there are a large number of such devices, the assembly can become considerably time consuming and difficult to assemble with conventional methods.
Also, with the use of threaded devices, there may also be a need for a lock washer, drilling and tapping of the heat sink and all of such operations and additional mounting hardware contributes to the cost of the manufacture. The screws used to attach the heat sink must also be torqued down precisely. If the screws are torqued too loosely, there is not sufficient heat conducting contact between the electronic component and the heat sink. On the other hand, if the torquing is too tight, there may be breakage or damage to the device.
In other heat sink assemblies, spring clips have been used to attach the heat sink to a frame having the electronic component in contact with the heat sink.
Accordingly, the present invention relates to an assembly for affixing a heat sink in a good heat conducting position to an electronic component that is readily manufacturable and assembled with mass production techniques. With the present invention, the need for mounting hardware is eliminated as is the requirement that there be any additional modifications made to the heat sink to mate it to the electronic component in a good heat conducting relationship. In addition, the present heat sink assemblies of this invention can be made in large quantity, mass produced modules easily and inexpensively and are adapted to be manufactured as various individual assemblies or module type of assemblies with multiple heat sinks.
Thus, the heat sink assembly of the present invention comprises a frame that has a bottom surface that is generally a flat surface and which has a plurality of guides that extend upwardly from the flat surface. As will be seen, therefore, there are preferably four guides that combine to form the corners of a rectangle and are dimensioned so that a rectangular electronic component can be placed in the space between the guides and moved toward the bottom surface of the frame and the inwardly narrowing space serves to accurately position the electronic component as it reaches the bottom surface. The frame also has a plurality of spring members that also extend outwardly from the bottom surface of the frame in the same direction as the guides and the spring members have a inwardly facing projections at the free ends thereof. Another preferred feature of the frame is that there may be a plurality of spring guides, also preferably molded into the frame and which project outwardly from the bottom surface to position a spring with respect to the frame as will later be explained. Also the frame may have an indexing protrusion extending outwardly from the bottom surface that interfits with the electronic component to guide that electronic component in the desired position in the heat sink when assembled and again, will be later explained.
As can be seen, all of the aforementioned features can be injection molded into a one piece construction and therefore can be produced relatively inexpensively in large quantities.
A spring is positioned on the bottom surface of the frame and within the space between the guides. The spring can be a generally central outwardly arched shape with the ends of the spring guided into the desired position against the bottom surface of the frame by means of the spring guides such that the spring can be easily and rapidly inserted into the proper position and be assured of being correctly located. The spring itself is preferably constructed of a metal material.
The electronic component is positioned atop of the spring in contact therewith and the electronic component preferably has an aperture that receives the indexing protrusion so that the electronic component can be inserted into the space between the guides where the indexing protrusion enters the aperture and guides the electronic component into its proper position.
Finally, there is a heat sink that is affixed to the frame in accordance with the present invention. The heat sink is basically a metal block having a generally planar surface and having a plurality of heat radiating fins that extend outwardly. In one preferred embodiment, the heat sink is extruded of aluminum and has two lateral exterior surfaces with the heat radiating fins being elongated in the same orientation as the lateral exterior surfaces as would be a result of the extrusion process. Each of the lateral exterior surfaces has an elongated ridge formed thereabout and which runs the entire length of each lateral exterior surface.
The heat sink is affixed to the frame by means of the interfitting of the inward projections at the free ends of the spring members that snap fit into the ridges formed about the lateral exterior sides of the heat sink and the location of the grooves and the designed length of the spring members is, of course, predetermined so that the heat sink is positioned at a desired location affixed to the frame and the planar surface of the heat sink is fully abutted against the surface of the electronic component so that the heat from the heat generating electronic component can be efficiently transferred to and dissipated through the heat sink. The heat sink is also guided in its seating within the frame as the heat sink enters the space between the guides.
The electronic component is forced or biased against the planar surface of the heat sink by means of the spring that is sandwiched between the bottom surface of the frame and the lower surface of the electronic component automatically creating the desired force of the electronic component against the heat sink.
As such, the present heat sink assembly is easily assembled and the force of the electronic component that holds it against the heat sink is predetermined and a known force is automatically established for good heat conductivity with no need for an assembler to take any action to set or adjust that force. The assembly of the present heat sink assembly is carried out by a simple one-step operation and therefore is conducive to mass production techniques that are relatively inexpensive and no additional physical alteration, such as drilling, tapping or the like of the heat sink is required that could add to the overall time to construct the heat sink assembly.